Re: [PATCH] virtio: Add function name to error messages

["Alex Bennée" <alex.bennee@linaro.org>]

Alessandro Ratti <alessandro@0x65c.net> writes:

> Replace virtio_error() with a macro that automatically prepends the
> calling function name to error messages. This provides better context
> for debugging virtio issues by showing exactly which function
> encountered the error.
>
> Before: "Invalid queue size: 1024"
> After:  "virtio_queue_set_num: Invalid queue size: 1024"
>
> The implementation uses a macro to insert __func__ at compile time,
> avoiding any runtime overhead while providing more specific error
> context than a generic "virtio:" prefix.
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/230
> Buglink: https://bugs.launchpad.net/qemu/+bug/1919021
>
> Signed-off-by: Alessandro Ratti <alessandro@0x65c.net>
> ---
>  hw/virtio/virtio.c         | 2 +-
>  include/hw/virtio/virtio.h | 4 +++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 9a81ad912e..44528d7f2b 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -3931,7 +3931,7 @@ void virtio_device_set_child_bus_name(VirtIODevice *vdev, char *bus_name)
>      vdev->bus_name = g_strdup(bus_name);
>  }
>  
> -void G_GNUC_PRINTF(2, 3) virtio_error(VirtIODevice *vdev, const char *fmt, ...)
> +void G_GNUC_PRINTF(2, 3) virtio_error_impl(VirtIODevice *vdev, const char *fmt, ...)
>  {
>      va_list ap;
>  
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index c594764f23..961d021497 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -249,7 +249,9 @@ void virtio_init(VirtIODevice *vdev, uint16_t device_id, size_t config_size);
>  
>  void virtio_cleanup(VirtIODevice *vdev);
>  
> -void virtio_error(VirtIODevice *vdev, const char *fmt, ...) G_GNUC_PRINTF(2, 3);
> +#define virtio_error(vdev, fmt, ...) \
> +    virtio_error_impl(vdev, "%s: " fmt, __func__, ##__VA_ARGS__)
> +void virtio_error_impl(VirtIODevice *vdev, const char *fmt, ...) G_GNUC_PRINTF(2, 3);
>  
>  /* Set the child bus name. */
>  void virtio_device_set_child_bus_name(VirtIODevice *vdev, char *bus_name);

For completeness you could also fixup:

  virtio_error(vdev, "%s: %d reason unknown", __func__, pnd->reason);

for virtio-ballon. Otherwise:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>


-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro